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2016-11-11lib/stackdepot: export save/fetch stack for driversChris Wilson1-0/+2
Some drivers would like to record stacktraces in order to aide leak tracing. As stackdepot already provides a facility for only storing the unique traces, thereby reducing the memory required, export that functionality for use by drivers. The code was originally created for KASAN and moved under lib in commit cd11016e5f521 ("mm, kasan: stackdepot implementation. Enable stackdepot for SLAB") so that it could be shared with mm/. In turn, we want to share it now with drivers. Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Chris Wilson <[email protected]> Cc: Andrey Ryabinin <[email protected]> Cc: Alexander Potapenko <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: Joonsoo Kim <[email protected]> Cc: "Kirill A. Shutemov" <[email protected]> Cc: Daniel Vetter <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2016-10-27lib/stackdepot.c: bump stackdepot capacity from 16MB to 128MBDmitry Vyukov1-1/+1
KASAN uses stackdepot to memorize stacks for all kmalloc/kfree calls. Current stackdepot capacity is 16MB (1024 top level entries x 4 pages on second level). Size of each stack is (num_frames + 3) * sizeof(long). Which gives us ~84K stacks. This capacity was chosen empirically and it is enough to run kernel normally. However, when lots of configs are enabled and a fuzzer tries to maximize code coverage, it easily hits the limit within tens of minutes. I've tested for long a time with number of top level entries bumped 4x (4096). And I think I've seen overflow only once. But I don't have all configs enabled and code coverage has not reached maximum yet. So bump it 8x to 8192. Since we have two-level table, memory cost of this is very moderate -- currently the top-level table is 8KB, with this patch it is 64KB, which is negligible under KASAN. Here is some approx math. 128MB allows us to memorize ~670K stacks (assuming stack is ~200b). I've grepped kernel for kmalloc|kfree|kmem_cache_alloc|kmem_cache_free| kzalloc|kstrdup|kstrndup|kmemdup and it gives ~60K matches. Most of alloc/free call sites are reachable with only one stack. But some utility functions can have large fanout. Assuming average fanout is 5x, total number of alloc/free stacks is ~300K. Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Dmitry Vyukov <[email protected]> Cc: Andrey Ryabinin <[email protected]> Cc: Alexander Potapenko <[email protected]> Cc: Joonsoo Kim <[email protected]> Cc: Baozeng Ding <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2016-07-28lib/stackdepot.c: use __GFP_NOWARN for stack allocationsKirill A. Shutemov1-0/+1
This (large, atomic) allocation attempt can fail. We expect and handle that, so avoid the scary warning. Link: http://lkml.kernel.org/r/[email protected] Cc: Andrey Ryabinin <[email protected]> Cc: Alexander Potapenko <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Rik van Riel <[email protected]> Cc: David Rientjes <[email protected]> Cc: Mel Gorman <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2016-05-05lib/stackdepot: avoid to return 0 handleJoonsoo Kim1-1/+5
Recently, we allow to save the stacktrace whose hashed value is 0. It causes the problem that stackdepot could return 0 even if in success. User of stackdepot cannot distinguish whether it is success or not so we need to solve this problem. In this patch, 1 bit are added to handle and make valid handle none 0 by setting this bit. After that, valid handle will not be 0 and 0 handle will represent failure correctly. Fixes: 33334e25769c ("lib/stackdepot.c: allow the stack trace hash to be zero") Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Joonsoo Kim <[email protected]> Cc: Alexander Potapenko <[email protected]> Cc: Andrey Ryabinin <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2016-04-28lib/stackdepot.c: allow the stack trace hash to be zeroAlexander Potapenko1-4/+0
Do not bail out from depot_save_stack() if the stack trace has zero hash. Initially depot_save_stack() silently dropped stack traces with zero hashes, however there's actually no point in reserving this zero value. Reported-by: Joonsoo Kim <[email protected]> Signed-off-by: Alexander Potapenko <[email protected]> Acked-by: Andrey Ryabinin <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2016-03-25mm, kasan: stackdepot implementation. Enable stackdepot for SLABAlexander Potapenko1-0/+284
Implement the stack depot and provide CONFIG_STACKDEPOT. Stack depot will allow KASAN store allocation/deallocation stack traces for memory chunks. The stack traces are stored in a hash table and referenced by handles which reside in the kasan_alloc_meta and kasan_free_meta structures in the allocated memory chunks. IRQ stack traces are cut below the IRQ entry point to avoid unnecessary duplication. Right now stackdepot support is only enabled in SLAB allocator. Once KASAN features in SLAB are on par with those in SLUB we can switch SLUB to stackdepot as well, thus removing the dependency on SLUB stack bookkeeping, which wastes a lot of memory. This patch is based on the "mm: kasan: stack depots" patch originally prepared by Dmitry Chernenkov. Joonsoo has said that he plans to reuse the stackdepot code for the mm/page_owner.c debugging facility. [[email protected]: s/depot_stack_handle/depot_stack_handle_t] [[email protected]: comment style fixes] Signed-off-by: Alexander Potapenko <[email protected]> Signed-off-by: Andrey Ryabinin <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Pekka Enberg <[email protected]> Cc: David Rientjes <[email protected]> Cc: Joonsoo Kim <[email protected]> Cc: Andrey Konovalov <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Konstantin Serebryany <[email protected]> Cc: Dmitry Chernenkov <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>